Liquid seal



March 19, 1940. J. M. HAlT LIQUID SEAL Filed June 18. 1958 2 Sheets-Sheet 1 March 19, 1940.

J. M. HAlT LIQUID SEAL Filed June 1e, 195s 2 Sheets-Sheet 2 Patented Mar. 19, 1940 PATENT OFFICE LIQUID SEAL James M. Bait, Los Angeles, Calif., assignor to Food Machinery Corporation, a corporation of Delaware Application June 1s, 193s, serial No. 214,529

12 Claims.

This invention relates generally to submersible well pumps wherein an electric motor and a system of pump impellers is submerged in the well liquid. More particularly, the invention relates to liquid seals for use in sealing a casing having a shaft extending thereinto for the purpose of preventing the liquid in which the casing and shaft are submerged from entering the casing.

The liquid seal of this invention is particularly designed for use in a submersible velectric motor having the shaft extending through the upper end of the motor casing. Ordinarily with this type o construction the liquid seal is located at the junction of the shaft and casing at the upper end of the motor. The conventional construction is to utilize a mercury cup mounted on the shaft and rotating therewith, into which -extends a stationary clipper or sleeve which depends from the motor casing. Since the sealing liquid, usually mercury, is heavier than either the internal or external liquids any loss of mercury from the cup caused by vibration, interruption in the operation of the pump, or emulsication, impairs the efeiency of the seal since the mercury escapes to the lowerportion of the motor. Any mercury escaping from the cup may damage the motor and this is a further disadvantage of the ordinary construction. l

Since the sealing liquid is the heaviest liquid dealt with, I have found it especially desirable to place the seal at the bottom of the motor and therefore it is an object of this invention to provide a liquid seal of simple form and construction below the motor proper of a submersible motor 3 having a shaft extending from the upper end of the motor casing.

The conventional type of mercury cup mounted on the shaft is apertured at the point of junction with the shaft and therefore provides an undesirable container for the sealing liquid. It is well known that mercury is an extremely difficult 'liquid to contain unless the container is a solid integral type of a non-porous material.

It is therefore an object of this invention to provide a liquid seal in which the container for the mercury is an integral solid bottom member with no sealing junctions or joints therein.

It has been found that when using a solid motor shaft it is necessary to employ a flexible connection between the motor shaft and the pump shaft in order to prevent vibrations being trans: ferred from the region of the impellers to the motor. It hasalso been found that by the use o'. a hollow motor shaft it is possible to eliminate the exible connection between the motor'shaft and the pump shaft due to the inherent flexibility of the long relatively slim pump shaft eX- tending throughout the hollow motor shaft. It is therefore a further object of this invention to provide a liquid seal which is particularly designed for use in connection with a hollow motor shaft.

n is a stm further object of this invention to provide an improved type of liquid seal which is designed to minimize skin friction losses and to minimize the amount of heat generated by the friction of the elements of the seal.

It is also an object of this invention'to provide an improved type of liquid seal of simple form and construction which utilizes stationary sealing members. This and other objects will be apparent from the drawings and the following description thereof. Referring to the drawings which are for illustrative purposes only:

Fig. 1 is a fragmentary sectional elevation of a submersible motor embodying the seal of this invention;

Fig. 2fis an enlarged sectional detail view of the seal of Fig. l;

Fig. 3 is a framentary sectional elevation of a submersible motor having no oil supply means and embodying the liquid seal of this invention;

Fig. 4 is an elevation partly in section, of a completely sealed submersible motorV having no oil supply means and embodying the liquid seal of this invention; Y

Fig. 5 is a fragmentary sectional elevation of a submersible motor showing a modified form of seal; and

Fig. 6 is a sectional elevation of another form of seal.

More particularly describing the invention, reference numeral Il generally indicates a submersible motor which is adapted to act as the motive power for a pump having a series of impellers located above the motor. This motor is suspended in the well in the ordinary manner below the pump impellers by means of the connecting pump inlet strainer I2.

The motor comprises a. motor casing generally indicated by reference numeral i3 which is made up of the shell I4, upper closure member I5, a cup I6 and a skirt I'l. Inside the shell there is mounted an Aordinary stator 20 which is provided with electrical cable means 2| for supplying current thereto from the surface of the ground. Inside` the stator is a rotor 22 which is mounted on a hollow rotor spindle or hollow motor shaft 23. The hollow motor shaft 23 is supported by upper and lower ends of the motor casing.

The motor shaft is provided with. a hub portion 21 at its lower end which has a threaded bore 28 adapted to accommodate the'pump shaft 29 on which the impellers of the pump are mounted. The pump shaft is radially supported at the upper end of the motor casing by the bearing 30. A. sand collar 32 is mounted on the shaft just above the bearing to prevent entrance of sand into the bearing region.

The particular motor shown in Fig. 1 is of the type adapted to be filled with gas, that is, coma pressed air, by means of the supply pipe 34. Thecompressed air keeps the external liquid of the well from rising in the skirt I1 above the en trance to the oil by-pass escape conduit 35. Lubrication of the bearings is accomplished by dripping oil down the line 34 and permitting the lubricant to work through the motor and dropto the surface of the external liquid at 36. From here oil may be by-passed to a point above the intake of the pump, that is, the strainer I2, by means of the oil by-passline 35.

Referring to Fig. 2 for details .in the construction of the liquid seal of this invention, it will be seen that the cup member I6 forms a stationary container for the reception of mercury 38. The hollow motor shaft 23 extends into this container below the level of the mercury therein. The pump shaft 29 is provided with a port 39 to establish communication between the interior of the lower end of the motor shaft and the exterior thereof in the region of the lower end of cup I8. With this construction the mercury is free to rise within the hollow motor shaft to the same level.

To effect a seal a stationary baille. tubeor dipper 40 is provided which is dependingly mounted from the upper closure member I5 of the'motor casing. This member extends down into the mercury and is preferably provided at its lower end with a portion 40 of Bakelite or stainless steel.

With this construction the external liquid or well liquid is confined to the space between the pump shaft and the interior of the stationary baiile 40 and cannot descend below the surface of the mercury between the pump shaft and the stationary baille. The internal liquid of the motor is confined to tlie space or region exteriorly `of the stationary baie 40 and contacts-the surface of the mercury between the motor shaft and the stationary baiile and also contacts the surface of the mercury between the cup I6 andthe motor shaft.

When the motor is not operating the mercury,

'assuming that the internal and external pressures are balanced, tends to assume the same.

heightin the cup I6 and within the motor shaft on both sides of the stationary baille (see Fig. 1). When the motor is operating a certain amount of pumping action takes place through the port 39 which causes the mercury to rise in the shaft'and assume a higher level therein than it assumes in the cup I6 (see Fig. 2). This tends to reduce the skin friction loss because of the fact that more mercury is brought into contact with the members of less diameter.

It is preferable to coat all surfaces which 'contact the mercury with a nonf'metallic lining and this has been indicated by reference numeral 42. However, if these-mercury contacting parts are formed of a metal not eifected by thebearings 24 and 25 located respectively at the mercury, such as stainless steel, a coating of nonmetallic material is unnecessary.

Referring to Fig. 3, there is shown a submersible motor generally indicated by reference numeral Il which differs from that shown in Fig. l by having an elongated closure 44 mounted below the shell I4 in place of the skirt I1. This motor is adapted to be filled with lubricant at the surface of the ground and noprovision is made for supplying lubricant to the motor after it is installed in place in the well. The top of the motor is the same as that shown in Fig. 4. A vent tube 45 which is in communication with the lower end of the closure member 44 is provided as a means of lbalancing the internal and external pressures of the internal and external liquids. The mercury seal above described is adaptable for use in this type cf installatio as shown in elevation at 46.

Referring to Fig. 4 there is shown another type Vof submersible motor in which the liquid seal above described may be used. In this figure the seal which is shown in elevation at 41, is used in connection with a. submersible'motor II which is completely sealed and is adapted to be filled with av supply of lubricant. In this case the cup I6 acts as the bottom closure for the motor shell I4.

A modified form of the invention is shown acts as the container'for the mercury and the cup I6 has no function except as an enclosing means for the lower end of the motor shaft.

In Fig. 6 there is shown another modified form.'

of the invention which is particularly designed to lessen skin friction loss. The motor shell indicated by reference numeral has a reduced threaded lower end portion 5I which is adapted to accommodate a cup or container 52. The motor is provided with a hollow motor shaft Il which is supported atI the uppery end of the motor as the shaft23 of Fig. 1 and which is supported at the lower end of the motor by means of the bearings 5l. This shaft extends into the cup 52. In this connection cup 52 is formed so as to provide a relatively narrow space -55 between the two elements. The motor shaft 53 has a hub portion '56 formed on its lower end and having a threaded bore 51 to accommodate the' pump shaft 58. In this form of the invention the pump shaft 58 is provided with an oblique port 59 adapted to establish communication between the space interiorly of the motor shaft and the cup 52.

A stationary tubular baille 50 is provided which is mounted at the upper end of the motor casport for the member 60.

The motor' shaft 5s is provided with radiaiiy extending ports 53 just above the hub portion forV the purpose of establishing communication to opposite sides of the motor shaft.

"In theoperation of this form of the invention, referring first to the left hand side of Fig. 6, wherein the mercury 3l is shown in the position which it tends to assume when the motor 7.5'

and having a hub at its lower end; a rotor onis not operating, it will be seen that the mercury is approximately evenly balanced on opposite sides of the shaft 53. When the motor is operating the port 59 in the pump shaft 58 creates a pumping action and causes the mercury tov rise in the space between the shaft 58 and the stationary baille 60 as indicated at the right hand side of Fig; 6. proportion of mercury is confined to the region between the pump shaft 58 and the stationary baffle 60 where it is in Contact with surfaces which are rotating at considerably less speed than the ,outer surface of the motor shaft 53. This construction greatly reduces the skin friction loss and makes for a more efficient seal. The ports 53' provide for by-passing liquid from the region between the motor shaft 53 and the stationary baille 60 to a region exteriorly of the motor shaft 53 so that the mercury may be pumped up'- wardly interiorly of the baffle 60.

As in the other forms of the invention, the

, mercury surface between the pump shaft 58 and cup whereby the baiiie 80 is in contact with the external liquid while the other surfaces of the mercury are in contact with the internal liquid.

I claim as my invention:

l. In a device of the bination of: a casing; a hollow shaft rotatably mounted in said casing, said shaft having a hub at its lower end; a second shaft mounted in the hub portion of said hollow shaft and extending through the upper end of said casing; a tubular baffle mounted in and extending downwardly therefrom within said hollow shaft surrounding said second shaft; and a sealing liquid in the lower end of said hollow shaft extending above the lower end of said tubular baffle. I

2. In a device of the class described, the combination of: a casing; a hollow shaft rotatably mounted in said casing, said shaft having a hub at its lower end; a second shaft mounted in the hub portion of said hollow shaft and extending through the upper end of said casing; said second shaft having a port in its lower end communication interiorly and exteriorly of said hollow shaft; a tubular baiile mounted in the upper end of said casing and extending downwardly therefrom within said hollow shaft and surrounding said second shaft; said .casing forming a cup surrounding the lower end of said hollow shaft; and a sealing liquid contained in said the sealing liquid stands in said hollow shaftI at a height above the lower end of said baille.

3. In a submersible motor, the combination of: a motor casing; a stator in said casing; a hollow motor shaft rotatably mounted in said casing,

said motor shaft being open at its upper end and having a hub at its lower end; a rotor on said motor shaft; a pump shaft mounted in the hub of said motor shaft and extending through the upper end of the motor casing; a tubular baflie mounted in the upper end of said casing and extending downwardly therefrom within said motor shaft surrounding said pump shaft; a bearing for radially supporting said pump shaft mounted in said baffle at the upper end thereof; and a sealing liquid in the lower end of said motor shaft extending above the lower end of said tubular baille.

4. In a submersible motor, the combination of: a motor casing; a stator in said casing; a hollow motor shaft rotatably mounted in said casing,

said motor shaft being open at its upper endl With this construction the greater class described, the comthe upper end of said casing establishing said motor shaft; a pump shaft mounted in the hub of said motor shaft and extending through the upper end of the motor casing, said pump shaft having a port in its lower end establishing communication interiorly and exteriorly of said motor shaft; a tubular baiiie mounted in the upper end of said casing and extending downwardly therefrom surrounding said pump shaft within said motor shaft; said motor casing forming a cup surrounding the lower end portion of said motor shaft; and a sealing liquid contained in said cup whereby the sealing liquid stands in said motor shaft at a height above the lower end of said baiile.

5. In a submersible motor for use in operating a well pump above the motor, the combination of: a motor casing forming a motor compartment and a surge chamber therebelow open to the well liquid, said compartment and said chamber being separated by an apertured partition; a stator in said motor compartment; a hollow motor shaft rotatably mounted in said motor compartment, said motor shaft being open at its upperend and having a hub at its lower end; a rotor on said motor shaft in said motor compartment; a pump shaft mounted in the hub portion of said motor shaft and extending through the upper end of the motor casing, said pump shaft having a port in its lower end establishing communication interiorly and exteriorly of said motor shaft; a tubular baffle mounted in the upper end of said casing and extending downwardly therefrom Within said motor shaft surrounding said pump shaft; said partition member between said motor compartment and said surge chamber forming a cup surrounding the lower end of said motor shaft; .a sealing liquid contained in said cup whereby the sealing liquid stands in said motor shaft at a height above the lower end of said baiile; conduit means for connecting the motor casing to a supply of compressed air and a supply of lubricant whereby said motor compartment and said surge chamber may be filled with compressed air to prevent entrance of well liquid; and a by-pass conduit leading from said surge chamber to a point above the intake of the pump.

6. In a device of the class described, the combination of: a casing; a hollow shaft rotatably mounted in said casing, said shaft having a hub at its lower end and having a port immediately above said hub; a second shaft mountedein the hub of said hollow shaft and extending through the upper end of said casing, said second shaft end of said casing and extending downwardlyv therefrom within said hollow shaft and surrounding said second shaft, said baffle having its lower end adapted to make a running fit with said hub of said hollow shaft, said baffle having an external flange intermediate its ends adapted to make a running fit with said hollow shaft; said casing forming a cup surrounding the lower end of said hollow shaft; and a sealing liquid contained in said cup above the height of said port in said'hollow shaft when said shaft is stationary.

7. In a submersible motor, the combination of: a motor casing; a stator in said casing; a hollow motor shaft rotatably mounted in said casing, said motor shaft being open at its upper end and having a hub at its lower end, said hollow shaft having a port immediately above said 4 i hub; a rotor on said motor shaft; a pump shaft mounted Vin the hub of said motor shaft and extending through the upper end of the motor casing; a tubular baiiie mounted in the upper end of said casing and extending downwardly therefrom' within said motor shaft and surrounding said pump shaft, said baiiie having its lower end adapted to make a running t with said hub on said motor shaft, said baille having an external ange intermediate its ends adapted to make a running fit with said motor shaft; said casing forming a cup surrounding the lower end of said motor shaft; and a sealing liquid contained in said cup above the height of said port in said motor shaft when said shaft is stationary.

8. A combination as defined in claim l in which the interior of said cup, andthe surfaces of said shafts in the region of said cup have a non-metallic coating.

9. A combination as defined in claim 1 in which the interior of said cup and the surfaces ofsaid Shafts in the region of said cup have a non-metallic coating, and in which the lower end of said baille is formed of a non-metallic material.

10. In a submersible motor, the combination of: a motor casing; a stator in said casing, a

hollow motor shaft rotatably mounted in said.

casing and having a hub at its' lower end; a rotor on said motor shaft; a pump shaft mounted in the hub of saidmotor shaft and extending through the upper end of the motor casing; means for eecting a liquid seal at the region of the lower ends of said shafts at a pointl below said stator and rotor.4

11. For use in combination with a submersible motor having a. casing, a hollow motor shaft, and a pump shaft mounted in said motor shaft and extending from the upper end o1 said cssing, means for eiecting a liquid-seal at the region of the lower end of said shafts comprising wall means forming a stationary container; a sealing liquidin said container; and a stationary baille extending into said container below the level of sealing liquid therein.

12. In a submersible motor, the combination of: a motor casing; a stator in said casing; a hollow motor shaft rotatably mounted in said casing; a rotor on said shaft, a pump shaft mounted inside of said hollow motor shaft; meansI for effecting a liquid seal at the region of the lower end of said motor and said pump shaft, including a stationary sealing liquid container,

a sealing liquid therein, and a stationary baille extending below the sealing liquid level.

M. HAIT. 

